Add a signal handler for SIGINT and SIGTERM, as well as sprinklings of
checks to abort_game. Although Ncurses DOES define handlers for SIGINT
and SIGTERM, they do not always seem to work correctly under many
operating systems.
The auto-generated files are created by running ./build-aux/bootstrap
with Gnulib as at commit d72683055ea46253d8eb8f89341eff5414ae6ca0 (with a
date stamp of Sun Jul 24 23:37:17 2011 +0200), Autoconf 2.68 and Automake
1.11.1.
In particular, the gnulib-tool utility now maintains lib/Makefile.am, as
well as many files in the m4 and lib directories. The file
m4/gnulib-cache.m4 allows the Gnulib files to be refreshed. See
http://www.gnu.org/software/gnulib/.
